Solenoid valves are useful for many applications requiring controlled fluid flow. For example, solenoid valves may be used to control hydraulic pressure in an automatic transmission of a vehicle. One type of solenoid valve, a variable force solenoid valve, is often used to apply a clutch for smooth shifting or to control transmission line pressure.
Problematically, however, existing solenoid valves often suffer from a lack of concentricity among components, particularly among magnetically-attractive surfaces. Such lack of concentricity may cause friction between components and a resulting reduced solenoid valve response. Therefore, many existing solenoid valves are unsuitable for applications requiring sensitive solenoid valve response for minimal hydraulic pressure changes.